Impact tool



2 Sheets-Sheet 1 IMPACT TOOL W. G. MITCHELL ETAL l3 ll Fmj.

Aug. 14, 1951 Filed A ril s, 1946 INVENTORS WALTER 6. MITCHELL LouisFosno-r ATTORNEY 1951 w. G. MITCHELL ETAL 2,564,224

IMPACT TOOL Filed April 8, 1946 2 Sheets-Sheet 2 y Lou/s P Fos/voT ATTOREV T 25 6 INVENTORS WALTER 6. MITCHELL FIG]. 7

Patented Aug. 14, 1951 IMPACT TOOL Walter G. Mitchell and Louis P.Fosnot, Aurora, 111., assignors to Independent Pneumatic Tool Company,Chicago, 111., a corporation of Delaware Application April 8, 1946,Serial No. 660,348

31 Claims. (01. 192-305) This invention relates to improvements inportable power operated impact tools for setting and removing nuts andbolts by power.

The invention, while relating to tools of the character referred to, isparticularly concerned with the impact clutch mechanism employed in suchtools to clutch and declutch the hammer and the anvil members of theclutch and for imparting rotational hammer blows on the anvil member totighten or loosen a nut or bolt being driven by the tool.

The invention has among its principal objects the following:

To provide an impact clutch construction in which the impact elements ofthe clutch are mounted for axial movement of the hammer member andindependently thereof to increase the strength and blow delivering powerof the clutch by having the hammer member provide extensive supportingand bearing surfaces for the impact elements throughout the major portion of their lengths and whereby the radial dimensions of the clutchare brought within limits for ease in handling and manipulation of thetool;

To provide means for controlling the registry between the impactelements on the hammer member and the abutment means on the anvil memberto limit the number of impact blows delivered per revolution of thehammer member in the operation of the tool;

To provide centrifugally responsive iiy-weights or equivalent means onthe hammer member to move the impact elements axially of the hammermember into the path of the abutments on the anvil member to clutch anddeliver hammer blows, respectively, on the anvil member in the operationof the tool; W

To provide cam means on the driving member of the clutch and acting onthe fly-weights to withdraw the impact means out of the path of theabutments to declutch the clutch in the relative rotation of the drivingand the hammer members;

To provide an impact clutch construction wherein the impact elements arein the form of rods extendible through the end portion of the hammermember opposed to the anvil member to engage and impart hammer blows onthe anvil member in the movement of the rods axially and independentlyof the hammer member; and

To provide a collar element on the hammer to hold the pivot pins for thefly-weights in place and against displacement by centrifugal force andvibration in the operation of the clutch device.

The invention consists further in the structural features andcombination of parts hereinafter described and claimed.

In the accompanying drawings:

Fig. 1 is a longitudinal sectional view with parts in elevation of aportable power operated impact tool containing an impact clutchmechanism of our invention; the upper or motor portion of the tool beingbroken away and the section being taken on line ll of Fig. 2 to show theimpact elements of the clutch device in positions to engage theabutments on the anvil member thereof;

Fig. 2 is a similar sectional view of the clutch unit removed from thetool and showing, in full lines, the centrifugally responsivefly-weights swung outwardly to engage the clutch; the section beingtaken on line 2-2 of Fig. 1;

Fig. 3 is a transverse sectional view taken on line 3-3 of Fig. 1showing, in full lines, the impact elements of the clutch device inengagement with their respective abutments on the anvil member;

Fig. 4 is a similar sectional view taken on line 4-4 of Fig. 1 showingthe cam means interposed between the driving member and the fly-weightsof the clutch;

Fig. 5 is a similar sectional view taken on line 5-5 of Fig. 1 to showthe relative positions and mounting of the impact elements and theflyweights, respectively, in the hammer member of the clutch;

Fig. 6 is a side elevational view of the clutch unit removed from thetool;

Fig. '7 is a similar view to show more in detail the locking connectionbetween hammer member and the collar element thereon to be hereinafterdescribed; and

Fig. 8 is a modified form of construction designed for use in largerheavy duty tools.

As shown in the drawings, the impact clutch device of our inventioncomprises a driving member I, an anvil member 2, and an interposedhammer member 3, all assembled in axial alignment by a clutch shaft 4and mounted for relative rotation in the forward casing section 5 of thetool. The hammer member 3 is a solid cylindric body of the desiredweight or mass and is mounted for rotation about the shaft 4 which isprovided on and fixed to the driving member I. The shaft 6 extendsaxially through the hammer member 3 and into a hollow spindle G on theanvil member 2. The spindle 6 journals the anvil member 2 for .rotationin the casing section 5 of the tool as shown in Fig. 1. The spindle 6terminates in a non-circular section 'I exterior of the tool case tomount and drive a nut or bolt engaging-socket 8 which is releasablyconnected with the spindle section I by a spring biased de tent pin 9 asshown in Fig. 1.

Mounted in the rear section ID of the tool casing is the tool motor IIfor driving the spindle 5 and the attached socket 8 through the clutchdevice of our invention in the operation of the tool, the motor II beingof the desired power operated type. A fluid pressure actuated rotarymotor is shown in Fig. l and in a motor of this type its rotor I2 withits radial blades or vanes i3 is located within a cylinder I l clampedwithin the tool case section I and held against rotation therein. Themotor II is of the reversible type for setting and removing nuts andbolts by the power of the tool. The tool is provided with the necessaryporting and pressure fiuid passage system to control the supply of fluidpressure or compressed air to the tool motor for operating it and areversible valve (not shown) is included in the tool assembly to controlthe direction of rotation of the tool motor as well understood in theart.

The driving member I of the clutch device has a disc-like member I atthe upper or inner end of the shaft 4 and extending over the adjacentend of the hammer member 3. Said disc I5 is integrally or otherwiserigidly connected with the shaft 4 and has a hollow central hub portionI5 aligned with the shaft 4 to couple the driving member I to the lowertrunnion section i! of the tool motor, therebeing a non-rotativeconnection between the parts for a direct drive between them. The hub I6and the trunnion I! are supported in the tool case in antifrictionbearings mounted therein as shown in Fig. 1, and which bearing assemblyprovides a journal to revolubly support the clutch unit within the toolcase at its end opposite to the anvil member 2.

Slidably mounted in the hammer member 3 are one or more impact elementsI8, I8, a pair of such elements being employed in the specificembodiment of the invention herein shown. The impact elements I8 arepreferably in the form of steel or other hardened rods mounted in thebody of the hammer member 3 in substantially para lel relation to eachother and to the clutch axis as defined by the shaft 4. By thisarrangement the hammer member 3 is provided with a pair oflongitudinally extending bores IBa, one for each rod I8, to provideextensive supporting and bearing surfaces for the rods I8 throughout themajor portion of their length to increa e the strength and blowdelivering power of the clutch. Also. with the rods I8 mounted in andextending axiallv of the hammer member 3, the clutching and impactaction of the clutch takes place b tween the opposed ends of the hammerand the anvil members about the shaft 4 and the radial and axialdimensions of the clutch device are materially reduced to bring theclutch construction within limits for ease in handling and manipulationof the tool.

The upper or inner ends of the rods I8, which are substantially of thesame length, extend into a cross-slot I9 in the hammer member 3 and areconnected together for movement in unison by a cross-member locatedwithin said slot as shown in Fig. 5. The cross-member '20 is slidablymounted on the shaft 4 where it extends through the slot I9 and saidrods I8 have rotative connection with the opposite ends of thecross-member 20 for self adjustment to distribute the wear on the loweror blow delivering ends of the rods by presenting difierentcircumferential portions thereof to the abutments on the anvil member 2to be presently described. The rotative connections between the rods I3and the cross-member 20 comprise bifurcations 2I, 2I in the oppositeends of the cross-member 20 to engage reduced neck portions 22, 22 onthe impact rods I8 as shown in Figs. 1 and 5.

The lower or blow delivering ends of the rods is are projectible beyondthe lower end of the hammer member 3 into and out of the path ofabutments 23,-24 provided on the radial wall 25 of the anvil member 2 toclutch and declutch the hammer and the anvil members 2, 3 and to imparta series of impacts or rotational hammer blows on the anvil member 2 atsaid abutments to tighten or loosen the nut or bolt being driven in theoperation of the tool. The end wall 25 of the anvil member 2 is opposedto and relatively close to the adjacent end of the hammer member 3 tolimit the axial extent of the clutch unit for compactness in design andto limit the amount of axial movement required of the impact rods I8 tobe moved into and out of the path of the abutments on the anvil memberin operation of the clutch.

With the foregoing in view, the abutments 23, 24 are at the ends ofarcuate slots 26, 21 provided in the anvil wall 25 to receive the rodsI8 when projected from the hammer member 3, as shown in Fig. 3. Theslots 26, 21 are concentric with the clutch axis and when in registerwith the rods I8 permit them to enter and engage the abutments to eitherclutch the hammer and the anvil members together as when driving a nutor bolt which is free to turn or deliver a series of rotational hammerblows on the abutments to tighten or loosen a nut or bolt when itresists the driving torque of the tool motor. The slots 26, 21 areelongated circumferentially and are of suflicient length to permit easyentry of the rods I8 into them and strike against the abutments at theends of the slots for substantially their full width.

Rotating the hammer member 3 in the direction of the arrows a in Fig. 3,the rods I8 engage the abutments 23 of the respective slots 26, 21 toset and tighten a nut or bolt with a right-hand thread or to loosenandunscrew a nut or bolt with a left-hand thread. Rotating the hammermember 3 in a reverse direction engages the rods I8 with the abutments24 of the slots for a reverse action of the clutch.

To control the number of impact blows delivered on the anvil member 2per revolution of the hammer member 3 relatively to the anvil member,the slots 26, 21 are disposed at different radial distances from theclutch axis as defined by the shaft 4. The same arrangement is followedin mounting the rods I8 in the hammer member 3. For example, the slot 26in the embodiment shown is arranged at a greater radial distance fromthe clutch axis 4 than the slot 21 and with a like arrangement for theimpact rods I8 in the hammer member 3, the impact rod I8 closest to theclutch axis functions only with the slot 21 while the other rod I8functions only with the slot 26. This is clearly indicated in Fig.

3, wherein it will be noted that the rods I8 register with the slots inone rotative position only of the hammer and the anvil members and inother positions are prevented from entry into the slots by theintervening anvil wall 25 as shown by the full and broken linepositions, respectively, of the rods I8 in Fig. 3. This limits theclutching and impact action of the clutch to once in each rotative cycleof the hammer member.

Mounted on the hammer member 3 are a pair of centrifugally responsivefly-weights 28, 28, one for each of the impact rods I8, and located inaxially extending chambers 29, 29 disposed on opposite sides of the slotI9 and intersecting the same as shown in Figs. 2. 5 and 6. The chambers29 are located between the rods I8 and allow lugs 38 adjacent the upperends of the fly-weights 28 to engage the cross-member 28 in grooves 3|.3| in the sides thereof. The lugs 38 have rounded outer ends for ease inoperation in the grooves 3| and serve to move the rods I8 by thecrossmember 20 towards and from the anvil member in the swingingmovement of the fiy-weights 28 by centrifugal force and a cam action,respectively.

The fly-weights 28 are pivoted on the hammer member 3 within thechambers 29 by pivot pins 32, 32, one for each fly-weight, and arrangedin transverse relation to the shaft 4. The pivot pins 32 are anchored inthe hammer member 3 by a collar element 33 to be presently described andshown in Figs. 1, 2, 5 and 6 of the drawings.

The fiy-weights 28 are preferably widened laterally at their outerswinging ends as shown in Fig. 6 to be rendered more responsive tocentrifugal force in the rotation of the hammer member 3. The chambers29 in the hammer member 3 are widened to conform to the increased widthof the fly-weights 28 and the latter co-qperate with the sides of therespective chambers 29 to be supported and guided thereby in theirswinging movement to actuate the impact rods I8.

The fiy-weights 28 are provided at their upper ends with rigid, upwardlyextending lugs 34, one on each fly-weight, and which lugs 34 extend intoperipheral recesses 35, 35 in the disc I5 of the driving member I of theclutch. These lugs 34 serve to connect the hammer member 3 with thedriving member I for rotation thereby and for actuating the fiy-weights28 to withdraw the impact rods I8 out of the slots 28, 21 to declutchthe anvil member 2.

The inner sides of the lugs 34 are rounded as shown in Fig. 4 for easein operation against the opposed edges of the recesses 35, the latterbeing diametrically disposed in the disc I5 to receive the lugs 34 andeach recess 35 has substantially the same shape as shown in Fig. 4 Inthis respect each recess 35 has a contour providing the recess with acentrally disposed deep portion b, and incline-d or camming portions, 0,c on opposite sides thereof to operate in reverse directions of rotationof the disc I5. Said inclined portions extend to and connect with theend portions d, d of the recesses.

The deep portions b, b of the recesses 35 allow the fly-weights 28 to bemoved by centrifugal force in the rotation of the hammer member 3 intothe full line positions shown in Fig. 2 to project the impact rods I8 totheir fullest extent into the slots 28, 21 in the anvil member 2 andclutch the latter with the hammer member 3 for rotation by the drivingpressure of the disc I5 against the sides of the lugs 34 when the nut orbolt engaged by the tool socket 8 is free to turn.

When rotation of the anvil member 2 is arrested by the tightened nut orbolt, the rods I8 strike the abutments 23 or 24 towards which they aredriven and the rotation of the hammer member 3 is momentarily halted atthe time of the impact reducing centrifugal force on the flyweights 28and allowing the driving disc I5 in its continued rotation under thetorque of the tool motor to move the cam-surfaces c with respect to thelugs 34 and swing the fly-weights 28 inwardly towards the shaft 4 asindicated by the broken line showing of the fiy-weights in Fig. 2.

The lugs 34 now are at the adjacent end portions d of the recesses 35and the hammer member 3 being declutched from the anvilmember 2 is againdriven by the driving pressure on the lugs 34. As the hammer member 3 isaccelerated under the drive of the tool motor centrifugal force againoperates on the fly-weights 28 swinging them outwardly and causing therods I8 to be projected into the slots 26, 21 to deliver furtherrotational hammer blows on the anvil member 2 at the abutments tofurther tighten or loosen the nut or bolt being driven by the tool. Theimpact action of the clutch repeats automatically and rapidly as long asthe tool remains applied to nut or bolt being driven. For a nut or boltto be tightened, the tool remains applied to the nut or bolt until thedesired tension is gained, whereupon the tool is removed from the work.For a nut or bolt to be unscrewed the tool remains applied to the nut orbolt until the same is loosened or removed as the case may require.

The dotted line showing in Fig. 4 shows the lugs 34 at one end of eachrecess 35 when the driving disc I5 has disengaged the rods I8 from theanvil member 2 and is beginning to accelerate the hammer member 3. Aspreviously mentioned in response to this action, centrifugal forceswings the fly-weights outwardly and moves their lugs 34 into the deeperportions 12 of recesses 35 in the disc I5 to engage the rods I8 with theanvil member 2. In the reverse rotation of the tool motor. the lugs 34are moved towards the opposite ends of the recesses 35 at d to againaccelerate the hammer member 3 and decrease any breaking action of therods I8 against the anvil member 2.

When the lugs 34 are at the ends at of the recesses 35 the rods I8 arecompletely withdrawn from the slots 25, 21 in the anvil member 2 asshown in the raised or withdrawn positions of the rods I8 in the brokenline positions in Fig. 1. At such time the driving pressure of the discI5 on the lugs 34 holds the lower end of the rods I8 out of rubbingcontact with the anvil wall 25 to avoid the breaking action abovereferred to. Hence, undue friction is avoided and the high efficiency ofthe tool is assured. The nut or bolt to be driven is marked 38 in Fig.1.

Inasmuch as the impact rods are mounted in the hammer member forrotation relative thereto, different impacting faces of the impact rodsare presented to the abutments at the ends of the slots upon eachsuccessive impact. This eliminates the concentration of wear at certainpoints on the impacting surfaces as is the case where impacting jaws arefixed relative to each other on both the anvil and the hammer member.This rotation of the impact rods is accomnlished prior to impact byfrictional engagement of the rods with the anvil. The impact rods I8after relative rotation between the hammer member and the anvil hasrecommenced, are moved downwardly by the fly-weights 28 so that thelower ends of the impact rods engage the top surface of the anvil andslide therealong in frictional contact therewith. The respective rods I8and the respective slots 24 are spaced at different distances from theaxis of rotation of the hammer and anvil and consequently the rods slidealong in frictional contact with the anvil until they are in registrywith their respective slots. When this registry has been established,the rods l3 move down and forwardly against the opposite ends or therespective slots for impacting engagement. As shown in Fig. 3, when theimpact rods I3 slide over the slots 24 with which they are not inregistry, a small fraction of their lower surfaces engages the marginalportions of the anvil adjacent those slots, and consequently a portionof the lower surfaces of the rods overhang these slots. Since the rodsare therefore in frictional contact with the anvil at those marginalportions of the slots with only a portion of their end surfaces,continued movement of the rods as the hammer rotates will efiect theirrotation relative to the hammer, the contact of the rods with the anvilbeing ofi center.

For larger heavy duty tools, we propose the arrangement shown in Fig. 8.Here, the flyweight 23a has a rotative bearing collar 31 or equivalenton its upper lug 38 to reduce friction between the lug and engaged edgeof the recess 35a in the disc la of the clutch driver la. Also, theanvil member 2a, is mounted on an antifriction bearing 39 interposedbetween the hammer member 3a and the anvil member 2a. Otherwise, theparts are substantially the same as hereinbefore described and shown.

Returning now to the collar element 33, the

latter has a tight or pressed fit on the hammer member 3 in enclosingrelation to the cross-slot l3 and extending slightly beyond the upperend of the hammer member 3 against which the disc I! has bearing asshown at e, e in Fig. 2. It is at these points that the lugs 34 on thefiy-weights 23 extend axially beyond the hammer member 3 and into therecesses 35 in the disc i5 as shown.

The disc l5 has a peripheral groove 40 to receive a flange structure 4!on the inner side of the collar element 33 as shown in Figs. 1 and 2.This flange structure 4| provides a guide for the disc is and isinterrupted so that lugs 34 may enter the recesses 35 in Fig. 4. Hence,the lugs 34 on the fly-weights 28 may contact the inner surface of thecollar element 33 to support the fly-weights 28 against the pressurethereon when driving the hammer member 3 relatively to the anvil member2.

The outer surfaces f, j of the fly-weights 28 on the lugs 34 conform tothe inner circular contour 9 of the collar 33 between the flanges 4| toeffectively support the fly-weights under the driving pressure of thedisc [5 thereon and relieve the pivot pins 32 of a shearing strain.

It will be noted that the pins 32 have their opposite ends in contactwith the inner surface of the collar 33 in Fig. 5, and that the ends ofthe pins are conical so that this contact will take place in anyrotative position the pins may assume. This contact of the pins 32 withthe collar 33 holds the pins 32 in place and against the forces set upin the operation of the clutch device, that is, against centrifugalforce in the rotation of the hammer member and against vibration in thehammering or impact action of the rods I8 on the abutments 23 or 24.

The collar 33 is held from rotation on the hammer member 3 by the tightfit'thereon and by the tongues 42 on the collar member interlocking withlugs or integral projections 43 on the hammer member on opposite sidesof the fly-weights 23'as shown in Figs. 6 and 7. To accomplish thislocking result. the tongues 42 flt into slots 44 8 formed between thelugs 43 as detailed in F18. 7. The tongues 42 are diametrically arrangedon the collar element 33 and the slots 44 have a complementarydisposition on the hammer member 3. The lugs 43 are interrupted at thechambers 23 so that collar member 33 does not hinder the outwardlyswinging movement of the fly-weights 23 by centrifugal force. This isapparent from the showing in Figs. 2 and 6.

The impact clutch of our invention is simple and inexpensive inconstruction and is adapted by its compact and unitary assembly to beincorporated in the outer casing of a portable power operated tool as inFig. 1. Moreover, with the impact elements l8 mounted for movementaxially of the hammer member 3 and independently'thereof the clutchingand impact action of the clutch may take place at the opposed endportions of the hammer and the anvil members and relatively close to thecluth axis to produce an efllcient and effective impact clutchconstruction for setting and removing nuts and bolts by power.

The details of construction and arrangement of parts shown and describedmay be variously changed and modified without departing from the spiritand scope of our invention, except as pointed out in the annexed claims.

We claim as our invention:

1. An impact clutch of the character described comprising, relativelyrotatable axially aligned, driving, hammer and anvil members, the hammerand the anvil members having axially opposed wall portions withabutments on the axially opposed .wall portion ofthe anvil member,impact means carried by and movable independently of the hammer memberinto and out of the path of the abutments on the axially opposed wallportion of the anvil member for clutching and declutching said last twomembers and for imparting rotational hammer blows on the anvil member atsaid'abutments in the relative rotation of said last two members,centrifugally responsive means carried by the hammer member for movingthe impact means into the path of said abutments, cam means on thedriving memberfor moving the impact means out of the path of saidabutments, and means for rotating the driving member.

2. An impact clutch of the character described comprising, relativelyrotatable hammer and anvil members arranged for rotation about a commonaxis, said members having axially opposed end wall portions withabutments on the end wall portion of the anvil member, impact rodsslidably mounted in the hammer member in substantially parallel relationto said axis, said rods being supported by the hammer member for thegreater portions of their lengths and movable through the end wallportion of the hammer member into and out of the path of the abutmentson the anvil member for clutching and declutching said members and forimparting rotational hammer blows on the anvil member in the relativerotation of the two members, centrifugally responsive means for movingthe impact rods into the path of said abutments, cammeans for moving theimpact rods out of the path of said abutments, and means for rotatingthe hammer member.

3. An impact clutch of the character described comprising, relativelyrotatable hammer and anvil members arranged for rotation about a commonaxis, said members having axially opposed end wall portions withabutments on the end wall a 9 portion 01' the anvil member, impact rodsslidably mounted in the hammer member and movable substantially parallelto said axis into and out of the path of the abutments on the end wallportion' of the anvil member for clutching anddeclutching said membersand for imparting rotational hammer blows on the anvil member at saidabutments in the relative rotation of the two members, centrifugallyresponsive flyweights pivoted on the hammer member for moving the rodsinto the path of the abutments, means for moving the rods out of thepath of said abutments, and means for rotating the hammer member.

4. An impact clutch of the character described comprising, relativelyrotatable hammer and anvil members arranged for rotation about a commonaxis, said members having axially opposed end wall portions withabutments on the end wall portion of the anvil member, impact rodsslidably mounted in the hammer member on opposite sides of said axis andmovable substantially parallel thereto into and out of the path of theabutments on the anvil member for clutching and declutching said membersand for imparting rotational hammer blows on the anvil member at saidabutments in the relative rotation of the two members, a cross-memberconnecting said rods, centrifugally responsive flyweights pivoted on thehammer member and acting on said cross-member for moving the rods intothe path of said abutments, means for moving the rods out of the path ofsaid abutments, and means for rotating the hammer member.

5. An impact clutch of the character described comprising, relativelyrotatable hammer and anvil members arranged for rotation about a commonaxis, said members having axially opposed end wall portions withabutments on the end wall portion of the anvil member, impact rodsslidably mounted in the hammer member on opposite sides of said axis andmovable sub- 7 stantially parallel thereto'into and out of the path ofthe abutments on the anvil member for clutching and declutching saidmembers and for imparting rotational hammer blows on the anvil member atsaid abutments in the relative rotation of the two members, across-member connecting said rods and having a rotative connectiontherewith, centrifugally responsive flyweights pivoted on the hammermember and acting on said cross-member for moving the rods into the pathof said abutments, means for moving the rods out of the path of saidabutments, and means for rotating the hammer member.

6. An impact clutch of the character described comprising, relativelyrotatable hammer and anvil members arranged for rotation about a commonaxis, said members having axially opposed end wall portions withabutments on the end wall portion of the anvil member, impact rodsslidably mounted in the hammer member on opposite sides of said axis andmovable substantially parallel thereto into and out of the path of theabutments on the anvil member for clutching and declutching said membersand for imparting rotational hammer blows on the anvil member atsaidabutments in the relative rotation of the two members, a cross-memberconnecting said rods, centrifugally responsive flyweights pivoted on thehammer member and operable on said cross-member for moving the rods intothe path of said abutments, means for moving the rods out of the path ofsaid abutments, and means forrotatins the hammer memher, saidcross-member having bifurcations engaging reduced portions of the rods.

'7. An impact clutch of the character described comprising, relativelyrotatable hammer and anvil members arranged for rotation about a commonaxis, said members having axially opposed end wall portions withabutments on the end wall portion of the anvil member, impact rodsslidably sponsive fly-weights pivoted on the hammer mounted on thehammer member on opposite sides of said axis and movable substantiallyparallel thereto into and out of the path of the abutments on the anvilmember for clutching and declutching said members and for impartingrotational hammer blows on the anvil member at said abutments in therelative rotation of said two members, a cross-member connecting saidrods, centrifugally responsive fly-weights pivoted on the hammer memberon opposite sides of said cross-member and engaging the same for movingthe rods into the path of said abutments, means acting on thefly-weights for moving the rods out of the path of said abutments andmeans for rotating the hammer member.

8. An impact clutch of the character described comprising, relativelyrotatable hammer and anvil members arranged for rotation about a commonaxis, said members having axially opposed end wall portions withabutments on the end wall portion of the anvil member, impact rodsslidably mounted in the hammer member and movable substantially parallelto said axis into and out of the path of the abutments on the anvilmember for clutching and declutching said members and for impartingrotational hammer blows on the anvil member at said abutments in therelative rotation of the two members, centrifugally responsivefly-weights pivoted on the hammer member for moving said rods into thepath of said abutments, lugs on the fly-weights, and driving meansoperating on said lugs for withdrawing the rods out of the pathof saidabutments and for rotating the hammer member.

9. An impact clutch of the character described comprising, relativelyrotatable hammer and anvil members arranged for rotation about a commonaxis, said anvil member having abutments on its portion opposed to thehammer member, impact means carried by the hammermember and movableindependently thereof into and out of the path of the abutments on theanvil member for clutching and declutching said members and forimparting rotational hammer blows on the anvil member at said abutmentsin the relative rotation of the two members, centrifugally remember onpivoted pins disposed transversely to and on opposite sides of said axisfor moving the impact means into the path of said abutments, anchoringmeans for said pins, means for moving the fly-weights out of the path ofsaid abutments, and means for rotating the hammer member.

10. An impact clutch of the character described comprising, relativelyrotatable hammer and anvil members arranged for rotation about a commonaxis, said anvil member having abutments on its portion opposed to thehammer member, impact means carried by the hammer member and movableindependently thereof into and out of the path of the abutments on theanvil member for clutching and declutching said members and forimparting rotational hammer blows on the anvil member at said abutmentsin the relative rotation of the two members, centrifugally responsivefly-weights pivoted on the hammer member on pivot pins at substantiallyright angles to said axis for moving the impact means into the path ofsaid abutments, a sleeve element fitted on the hammer member about theends of said pins for anchoring the same in the hammer member, means formoving the flyweights in the opposite direction to withdraw the impactmeans out of the path of said abutments, and means for rotating thehammer member.

11. An impact clutch of the character described comprising,- relativelyrotatable hammer and anvil members arranged for rotation about a commonaxis, said anvil member having abutments on its portion opposed to thehammer member, impact means carried by the hammer member and movableindependently thereof into and out of the path of the abutments on theanvil member for clutching and declutching said members and forimparting rotational hammer blows on the anvil member at said abutmentsin the relative rotation of the two members, centrifugally responsivefly-weights pivoted on the hammer member on pivot pins at substantiallyright angles to said axis for moving the impact means into the path ofsaid abutments, a sleeve element fitted on the hammer member about theends of said pins for anchoring the same in the hammer member, aninterfitting connection between the hammer member and the sleeve forholding the latter against rotation on the hammer member, means formoving the fly-weights in the opposite direction to withdraw the impactmeans out of the path of said abu ments, and means for rotating thehammer member.

12. An impact clutch of the character described comprising, relativelyrotatable, axially aligned, hammer and anvil members having axiallyopposed wall portions with abutments on the axially opposed wall portionof the anvil member, impact rods slidably mounted in the hammer memberand movable substantially parallel to said axis into and out of the pathof the abutments on the anvil member for clutching and declutching saidmembers and for imparting rotational hammer blows on the anvil member atsaid abutments in the relative rotation of the two members,centrifugally responsive means carried by the hammer member for movingthe rods into the path of said abutments, means for moving the rods outof the path of said abutments, and means for rotating the hammer member,said rods and said abutments being arranged to provide for apredetermined number of impacts per revolution of the hammer member.

13. An impact clutch of the character described comprising, relativelyrotatable, axially aligned, hammer and anvil members having axiallyopposed end wall portions with arcuate slots in the end wall portion ofthe anvil member and provid ing abutments at the ends of said slots,impact rods slidably mounted in the hammer member and movable axiallythereof into and out of the path of the abutments as provided by saidslots for clutching and declutching said members and for impartingrotational hammer blows on the anvil member at said abutments, means formoving the rods into and out of said slots, and means for rotating thehammer member.

14. An impact clutch of the character described comprising, relativelyrotatable, axially aligned, hammer and anvil members having axiallyopposed end wall portions with arcuate slots in the end wall portion ofthe anvil member and providingabutments at the ends of said slots,impact rods slidably mounted in the hammer member and movable axiallythereof into and out of the path of the abutments as provided by saidslots for clutching and declutching 12 said members and for impartingrotational hammer blows on the anvil member at said abutments, means formoving the rods into and out of said slots, means for rotating thehammer member, said rods and slots registering in one rotative positiononly of the hammer member relatively to the anvil member.

15. An impact clutch of the character described comprising, relativelyrotatable, axially aligned, hammer and anvil members having axiallyopposed and wall portions with arcuate slots in the end wall portion ofthe anvil member and providing abutments at the ends of said slots,impact rods slidably mounted in the hammer member and movable axiallythereof into and out of the path of the abutments as provided b saidslots for clutching and declutching said members and for impartingrotational hammer blows on the anvil member at said abutments, means formoving the rods into and out of said slots, and means for rotating thehammer member, said rods and slots being concentric to the clutch axisand disposed at different radial distances therefrom to register therods with the slots in one rotative position only of the hammer memberrelatively to the anvil member.

16. An impact clutch of the character described comprising, relativelyrotatable, axially aligned, driving, hammer and anvil members, saidhammer and anvil members having abutments on the portion of the anvilmember axially opposed to the hammer member, impact means carried by andmovable axially of the hammer member into and out of the path of theabutments on the anvil member for clutching and declutchin said membersand for imparting rotational hammer blows on the anvil member at saidabutments in the relative rotation of the two members, centrifugallyresponsive flyweights pivoted on the hammer member for moving the impactmeans into the path of said abutments, said driving member havingrecesses therein provided with cam contours, said flyweights having lugscoacting with said cam contours for withdrawing the impact means fromthe path of said abutments in the relative rotation of the driving andthe hammer members, and means for rotating the drivin member.

17. An impact clutch of the character described comprising, relativelyrotatable, driving. hammer and anvil members, said anvil member havingabutments, impact rods slidably mounted in the hammer member and movableaxially thereof into and out of the path of said abutments to clutch anddeclutch the hammer and the anvil members and to impart rotationalhammer blows on the anvil member in the relative rotation of said twomembers, centrifugally responsive means carried by the hammer member formoving the rods into the path of said abutments, and cam-means on thedriving member for moving the rods out of the path of said abutments andexerting a drivin pressure on the rods for holding the same out of thepath of the abutments until moved by centrifugal force into the path ofthe same.

18. An impact clutch of the character described comprising, relativelyrotatable driving, hammer and anvil members, impact means interposedbetween said hammer and anvil members to clutch and declutch the sameand to impart rotational hammer blows on the anvil member in therotation of the hammer member with respect to the anvil member, saidimpact means including centrifugally responsive fly-weights pivoted onthe hammer member for actuating said impact means, cam-recesses in thedriving member and having relative deep and connected inclined portionsto co-act with said fly-weights, and means for rotating the drivingmember.

19. An impact clutch of the character described comprising, relativelyrotatable drivin hammer and anvil members, impact means interposedbetween said hammer and anvil members to clutch and declutch the sameand to impart rotational hammer blows on the anvil member in therotation of the hammer member with respect to the anvil member, saidimpact means including centrifugally responsive fly-weights pivoted onthe hammer member to actuate said impact means, cam-means on the drivingmember for rotating the hammer member by exerting a driving pressure onthe fly-weights, means on the hammer member to relieve the pivots of thefly-Weights of said driving pressure, and means for rotating the drivingmember,

20. An impact clutch of the character described comprising, relativelyrotatable driving, hammer and anvil members, impact means interposedbetween said hammer and anvil members to clutch and declutch the sameand to impart rotational hammer blows on the anvil member in therelative rotation of the hammer and the anvil members, said impact meansincludin a centrifugally responsive fiy-weight pivoted on the hammermember to actuate said impact means and having an axially extending lugthereon, a revoluble bearing element on said lug, cam-means on thedriving member and acting on the fly-weight through said bearinglugjandmeans for rotating the hammer member.

21. An impact clutch comprising, relatively rotatable hammer and anvilmembers, the anvil members havin abutments thereon, impact means carriedby the hammer member and movable into and out of the path of saidabutments for clutching and declutching said members and for impartingrotational hammer blows on the anvil member at said abutments in therelative rotation of the two members, centrifugally responsivefly-weights pivoted on the hammer member for moving the impact meansinto the path of said abntments, a driving member having cam-meansoperating on said fly-weights for moving the impact means out of thepath of said abutments, and means for rotating the driving member, saidcam-means acting on the ends of the fly-weights opposite to the endsthereof coacting with said abutments.

22. In an impact clutch of the character described comprising, anoperative assembly of relatively rotatable hammer and anvil members,means on the anvil member providing arcuate paths and associatedabutments, impact means on said hammer member and movable independentlythereof into and out of said paths and the abutments associatedtherewith for clutching and declutching said hammer and anvil membersand for imparting rotational hammer blows on the anvil member at saidabutments in the relative position of said two members, means for movingsaid impact means into and out of the paths of said abutments, and meansfor rotating said hammer member, said paths and associated abutmentsbeing arranged for the impact means to engage the abutments on onerotative position only of the hammer member relatively to the anvilmember.

23. In an impact wrench, the combination of,

an operative assembly of relatively rotatable hammer, anvil and drivingmembers, means providing abutments on the anvil member in opposition tothe hammer member, impact means on the hammer member and movablerelatively thereto into and out of the path of said abutments forclutching and declutching said hammer and anvil members and forimparting rotational impacts on the anvil member at the abutments in therelative rotation of the hammer and the anvil members, cam-means on thedriving member and co-acting with said impact means for controlling themovement thereof into and out of the path of said abutments, saidcammeans having means enabling centrifugal force to project the impactmeans into the path of said abutments and means responsive to the torqueof the driving member to allow the latter to retate ahead of the hammermember to withdraw the impact means out of the path of the abutmentsfollowing an impact blow thereon.

24. In an impact wrench, the combination of, an operative assembly ofrelatively rotatable hammer, anvil and driving members, means providingabutments on the anvil member in opposition to the hammer member, impactmeans carried by and rotatable with the hammer member, said impact meansbeing movable relatively to the hammer member into and out of the pathof said abutments for clutching and declutching said hammer and anvilmembers and for impartin rotational impacts on the anvil member at theabutments in the relative rotation of the hammer and anvil members, saidimpact means being movable by centrifugal force into the path of saidabutments, cam-means on the driving member and co-acting with saidimpact means for controlling the movement thereof with respect to said'abutments, said cam-means cooperating with, said centrifugal force andsaid driving member, respectively, whereby the hammer member may moveahead of the cam-means before impact of the impact means with theabutments so that the cam-means may move for-' wardly relatively to thehammer member after impact to positively withdraw the impact means fromthe path of said abutments, and means for rotating the driving member.

25. In an impact wrench, an assembly of relatively rotatable hammer,anvil and driving members, abutments on the anvil member in oppositionto the hammer member, impact elements mounted on the hammer member andmovable into and out of the path of said abutments to clutch anddeclutch the hammer and anvil members and to impart rotational hammer,blows on the anvil member in the relative rotation of the two members,centrifugally responsive means carried by the hammer for movingtheimpact elements into the path of said abutments, and cam means on thedriving member in engagement with the centrifugal means for moving theimpact elements out of the path of said abutments after impact, said cammeans having bearing surfaces engageabie by' said centrifugal meansenabling the hammer member to rotate under centrifugal force ahead ofthe driving member before impact of the impact elements with theabutments by movement of said centrifugal means in one directionrelative to and against said bearing surfaces and allowing the drivingmember to rotate ahead of the hammer member and impact elements bymovement of said centrifugal means in the other direction relative toand against said bearing surfaces to withdraw the impact elements out ofthe path of the abutments followin the impact blow thereon.

26. An impact clutch of the character described comprising relativelyrotatably hammer and anvil members, the hammer and the anvil membershaving opposed wall portions with abutments on the opposed wall portionof the anvil member, impact means carried by and movable independentlyof the hammer member into and out of the path of the abutments on theopposed wall portion of the anvil member for clutching and declutchingsaid members and for imparting rotational hammer blows on the anvilmember at said abutments in the relative rotation of said members,centrifugally responsive means also carried by the hammer and pivotedthereto and operably connected with the impact means for moving theimpactmeans into the path of said abutments, cam-means for moving theimpact means out of the path of said abutments, and means for rotatingthe hammer member.

2'7. In an impact clutch of the character described, the combination ofrelatively rotatable, axially aligned hammer, anvil and driving members,means providing abutments on the anvil member in opposition to thehammer member, impact means rotatably mounted on said hammer member forrotation with and for rotation relative to said hammer member, saidimpact means being movable axially relative to the hammer member intoand out of the path of said abutments for clutching and declutching saidhammer and anvil members and for imparting rotational hammer blows onthe anvil member at the abutments in the relative rotation of the hammerand anvil members and being rotatable relative to said hammer memberprior to impacting engagement for presenting a different impacting faceto said abutment upon each successive impact, means for moving theimpact means into and out of the path of said abutments, and means forrotating the hammer member.

28. In an impact clutch of the character described, the combination ofrelatively rotatable, axially aligned hammer, anvil and driving members,means providing abutments on the anvil member in opposition to thehammer member,

impact means rotatably mounted on said hammer member for rotation withand for rotation relative to said hammer member, said impact means beingmovable axially relative to the hammer member into and out of the pathof said abutments for clutching and declutching said hammer and anvilmembers and for imparting rotational hammer blows on the anvil member atthe abutments in the relative rotation of the hammer and anvil members,said anvil having means engageable with said impact means for effectinglimited rotation thereof relative to the hammer member prior toimpacting engagement to cause said impact means to present a differentimpact face to said abutment upon each successive impact, means formoving the impact means into and out of the path of the abutments, andmeans for rotating the hammer member.

29. An impact clutch of the character described, comprising relativelyrotatable, axially aligned hammer and anvil members having axiallyopposed wall portions with arcuate slots in the end wall portion of theanvil member and providing abutments at the ends of the slots, impactrods rotatably and slidably mounted on said hammer member for rotationwith and for rotation relative to said hammer member and for axialmovement thereof into and out of the path of the abutments for clutchingand declutching said members and for imparting rotational hammer blowson the anvil member at said abutments, each impact rod being adapted toregister with one respective slot and to overhang and frictionallyengage with a portion of its end the marginal portion of another slotwith which it is out of registry whereby said rods will be rotated priorto impact relative to the hammer member to cause said rods to presentdifferent imp-acting faces to said abutments upon each successiveimpact, means for moving the impact rods into and out of the path of theabutments, and means for rotating the hammer member.

30. An impact clutch of the character described comprising relativelyrotatable, axially aligned hammer and anvil members having axiallyopposed end wall portions with arcuate slots in the end wall portion ofthe anvil member and providing abutments at the ends of the slots,impact rods slidably mounted in the hammer member and movable axiallythereof into and out of the path of the abutments as provided by saidslots for clutching and declutching said members and for impartingrotational hammer blows on the anvil member at said abutments, saidabutments and rods having impacting faces adapted to be engaged uponimpact and said impacting faces being disposed in parallel planes whichare parallel with the axis of said hammer and anvil, means for movingthe rods into and out of said slots, and means for rotating the hammermember.

31. An impact clutch of the character described comprising relativelyrotatable, axially aligned hammer and anvil members having axiallyopposed end wall portions with arcuate slots in the end wall portion ofthe anvil member and providing abutments in the ends of the slots,impact rods slidably mounted in the hammer member and movable axiallythereof into and out of the path of the abutments as provided by saidslots for clutching and declutching said members and for impartingrotational hammer blows on the anvil member at said abutments, means formoving the rods into and out Of the slots, said means operating on theend portions of the rods opposite the ends thereof which are engageablewith the anvil member, and means for rotating the hammer member.

' WALTER. G. MITCHELL.

LOUIS P. FOSNOT.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Num er Name Date 1,730,890 Kaisser Oct. 8, 19292,196,589 Jimerson Apr. 9, 1940 2,219,865 Fitch Oct. 29, 1940 2,219,883Amtsberg Oct. 29, 1940 2,326,347 Forss Aug. 10, 1943 2,339,530 VanSittert Jan. 18, 1944 2,339,531 Van Sittert Jan. 18, 1944

